1. Field of the Invention
The invention relates generally to pressure and flow rate control of fluid materials such as gas or liquid and, more particularly, but not by way of limitation, it relates to an improved flow rate controller that is responsive to fluid flow pressure to maintain a constant flow rate.
2. Description of the Prior Art
Applicants are aware of no prior art that functions in the manner of the present invention wherein fluid pressure within a flow way is directly utilized to control fluid flow through an orifice in such manner that a constant flow rate can be maintained. There are a number of prior teachings wherein responsive members have been placed in a fluid stream for the purpose of providing a force indication to an external monitoring or actuating facility. U.S. Pat. No. 3,269,181 in the name of Seay illustrates one form of flow responsive device that is responsive to solids flow, but the end function of this device is entirely different and provides no form of fluid flow regulation. Still other prior methods employ the basic steps of flow rate sensing with servo-controlled orifice adjustment, a very common type of flow control, but one that functions independently of the fluid pressure of fluid material within the conduit.
Differential pressure, as sensed across an adjustable metering orifice, is used on an automatic flow rate controller of a type that is commercially available from the W. A. Kates Co. of Deerfield, Ill. This controller utilizes a system of parallel fluid flow for regulation, one branch flowing through a first adjustable orifice, the other branch applying upstream pressure to vary a second orifice or flow passage. Yet another type of flow control valve may be identified as the Griswold valve. This valve provides in-line, pressure responsive control members for maintaining constant flow rate within a preselected pressure range. The control structure includes a spring loaded cup with specially designed orifices for movement in response to downstream pressure to regulate total fluid passage. In this case the tortuous cup orifices provide the total fluid passage at the rated maximum pressure flow rate along with any fluid flow at greater pressures.